Electrometer vacuum tube



Patented Aug. 10, 1948 UNITED STATES ELECTROMETER VACUUM TUBE AugusteLouis Marie Antoine Rouy, New York, N. Y., assignor to L. L. H. Company,Erie, Pa., a partnership comprising Hugh 0. Lord, Thomas Lord, andBlanche M. Hartman Application December 22, 1944, Serial No. 569,403

6 Claims. (01. 250-275) My invention relates broadly to electrometer isa transverse sectional view taken on line 3-3 vacuum tubes and moreparticularly to an imof Fig, 1; and Fig. 4 is atheoretical viewillustratproved construction of highly sensitive electroming the effectof the shield in the electrometer eter vacuum tube. vacuum tube of myinvention in effecting mutual This application is a continuation-in-partof 5 cancellation of electron and ion charges upon the my applicationSerial No. 552,892 filed Septemsurface of the shield in the electrometervacuum her 6, 1944, for Electrometer vacuum tube. tube.

One of the objects of my invention is to pro- In my co-pendingapplication 552,892, supra, I

vide an improved construction of electrometer have explained thefunctions of an electrometer vacuum tube having means for increasing theto vacuum tube in the measurement of very small sensitivity of theelectrometer tube. currents or voltages where the total amount ofAnother object of my invention is to provide a energy is extremely lowsuch as, for instance, in construction of electrometer vacuum tubeconthe case of voltages produced by pressure on a taining control grid,cathode and anode elecpiezo electric quartz crystal cell. I have pointedtrodes containing means for effecting mutual out that it is of theutmost importance to avoid cancellation of electron and ion charges uponany losses of the minute charge delivered to the the surface of a shieldsurrounding the control control grid of the electrometer vacuum tube. Igrid. have discovered that the sensitivity of the elec- Still anotherobject of my invention is to protrometer vacuum tube of my invention asset vide an improved construction of electrometer forth in applicati 55.8 Supra. y be sub vacuum tube containing a control grid, a cathodestantially increased by protecting the control grid system and an anodeelectrode with a shield of of the e ect ometer tube against ybombarddielectrlc material interposed between the conment by electronsreleased from the cathode systrol grid and the cathode system forpreventing term or against the attachment of any positive electrons fromthe cathode system from bomions liberated by the electronic bombardmentof barding the control grid. the anode. To effect cancellation of suchelec- Still another object of my invention is to protrons and ion chargwit spe t to the control vide a construction of electrometer vacuum tubeg d, I v de a Cyhnder of q a glass spaced including a control grid, a.cathode system and th sp t to t e Control grid a d a ra e to an anodeelectrode with a shield of dielectric enclose the control grid forobstructing the conmaterial interposed between the control grid and trolgrid against any b rdment by electrons cathode system for preventin anypositive ions emanating from the cathode system and at the which areliberated by electrical bombardment S e e preventing e attachment to t e00 of the anode from reaching the control grid. trol grid of anypositive ions which are liberated Still another object of my inventionis to proy t electronic bombardment f the anode. vide a construction ofquartz or glass shield for The s i ions. a d the tr ns arrying a thecontrol grid of an electrometer vacuum tube, negative charge ofelectricity fall upon the outer including acontrol grid, cathode systemand ansurface of the glass or quartz tube and their ode, which allowsacceleration of electrons from e a electrical Charges ancel each otheron the cathode system toward the anode through the surface of t e glassor quartz tube. However,

the field created by Voltage applied to th grid the acceleration ofelectrons from the cathode While obstructing the flow of electrons fromthe system t ward th an d th u h th field crecathode system to the gridand preventin the ated by the voltage applied to the control gridattachment upon the grid of ions liberated by is not affected by thepresence of the glass or the electron bombardment of the anode. quartzscreen. The grid current of the electrom- Other and further objects ofmy invention reeter tube is thus maintained absolutely negligiside inthe improved construction of electromble regardless of the voltageapplied to the coneter vacuum tube as set forth more fully in the trolgrid for thus increasing the sensitivity of the specificationherein-after following by reference electrometer vacuum tube foroperation under to the accompanying drawings in which: contro1 of thevoltages applied to the control grid.

Figure 1 is a vertical sectional view taken Referring to the drawings indetail the electhrough the electrometer vacuum tube of my intrometervacuum tube is represented as enclosed vention showing the quartz orglass shield enby an envelope I which may be formed in two closing thecontrol grid; Fig. 2 is a transverse secparts having relatively wideflanges 2 and 3 abuttional view taken on line 2-2 of Fig. 1; Fig. 3 tingface to face and serving as supports for the ring member H and projectradially, inwardly.

and serve as cantilever supports for the upper ends of filaments l'l, I8and 19' constituting the; cathode system. The lower ends of thefilaments ll, l8 and (9 are supported-bythetripod member 20 whichprojects through theendof' the envelope of the electrometerivacuum-tubeand terminates at 2! forming an electrical connection for the cathodesystem. The opposite electrical connection. for the cathode system ismade to radially extending 'memberfl or. any zother of the supportingrods that connect to the ringmember' H. Thus the cathodesystemis-maintained taut under the action of the spring arms I4,- l and. is asthe filaments are heated.

The control grid for the electrometer vacuum tube is represented at 22entering the envelope of the electrometer Vacuum tube throughthe end asrepresented at 23 and extending axially of the tube and centrally withrespect to the cathode system'forrned by filaments I'l, l8 and I9 andcylindrical anode l.

The's'hield of my invention'consists of a glass or quartz tube 24 whichincloses the control grid 22 and extends thereover in'spaced relationwith respect thereto. The glass or quartz tube 24 has-one end thereofflanged as represented at 25 within which ring member 26 is embedded.Ring member 26 serves as a'mechanical support for the relatively fragileglass or quartz tube 24. The ring member 25 is supported with respect toring member H through arm 21 which extends radially to ring llintroducing suificient flexibility into the support to prevent'shattering'oi the quartz or the glass tube 24 under conditioner shockvibration. The ring member 26 is normally supported out of the plane ofring member I l ailowlng suificient displacement between the end 22a ofgrid .22 and the closed end 24a of tube 24 to prevent breakage of theshield .24 under 'condition of vibration.

As illustratedin Fig. 4 the electrons emanating from the filaments ofthe cathode system shown at H, l8 and ii are collected by anode 1,

but are prevented from bombarding control grid 22 by the interpositionof the dielectric. shield 25. I have represented a path of electronsfrom filament 9 at 28, for example, being. deflected at 29 by shield 25anddirected toward the anode.

l at 38. Ions liberated by bombardment of the anode 1 may take a path,for example, .as representedat 3!, but because of the interposition .ofdielectric surface 24 the ions are prevented from reaching control grid22. electrons and ion charges upon the surface of shield 24 is effected,thus preventing increase in grid current. The grid current is maintainedabsolutely negligible regardless ofthe voltage applied to the grid andthe sensitivity and. eficiency of the electrometer tube increased.

While I havev described'my invention. in one of its preferredembodiments I realize that modiiications may .be made and I desire that'it be understood that no limitations upon mycinven- Mutual cancellationof 4 tion are intended except as may be imposed by the scope of theappended claims.

What I claim and desire to secure by Letters Patent of the United Statesis as follows:

1. An electrometer tube comprising an envelope enclosing a, controlgrid, a cathode system, and an: anode, a shield of dielectric materialsurrounding said control grid and interposed between said control gridand said cathode system and means resiliently suspending said shieldwithin said envelope in spacial relation to the control grid interiorlyof said shield and in spacial relation to said cathode system exteriorlyof said shield.

2; An electrometer tube comprising an envelope enclosing a control grid,a cathode system, and

an anode, a quartz shield surrounding said control grid and interposedbetween said control grid and said cathode system and means resilientlysuspending said shield within said envelope in spacial relation to thecontrol grid interiorly of said shield and in spacial relation to saidcathode system exteriorly of said shield.

3. An electrometer tube comprising an envelope enclosing a control grid,a cathode system, and

anode, supporting means for said cathode system Within said envelope, atube of dielectric material surrounding said control grid and spaciallyrelated thereto and disposed between said cathode system and saidcontrol grid, and means connected with said supporting means andresiliently suspending said tube of dielectric material formovementunder conditions of shock vibration without abutment with said controlgridor said cathode system.

4-. An electrometer tube comprising an envelope enclosing a controlgrid, a cathode system,. and an anode, a tubular member of dielectricmaterial surrounding said control grid and interposeddn spacial relationbetween said control grid and said cathode system for shielding saidcontrol grid against bombardment of electrons from said cathode systemand from ions liberated by electronic bombardment of said anode, andmeans supporting said tubular member for axial or transverse .movementwith respect to said control grid.

5. An electron discharge device comprising an enclosing vessel, a gridelectrode supported axially withinasaid vessel, a cylindrical anodeelectrode surrounding said grid electrode, a ring-like memberconcentrically disposed with respect to said gridelectrode and spacedfrom both said grid and anode electrodes, a multiplicity of filamentelectrodes supported by said ring-like member and extending inequidistant positions between said grid and anode electrodes, meanssupporting said ring-dike member and said anode electrode for minimizingdisplacement of said electrodes under conditions of vibration wherebysuch displacement of said electrodes which may occur takes place in thesame direction, a dielectric shield surrounding said grid electrode andinterposed between said grid electrode and said filament electrodes,said dielectric shield being spacially related with respect to both saidgrid electrode and said filament electrodes and means extendingirorntsaid ring-like member supporting said dielectric shield subject todisplacement under conditions of vibration without abutment with eithersaid grid or filament electrodes.

6. An electron discharge device comprising an encloslng'vessel, a gridelectrode supported axially withinisaid vessel, a cylindrical anodeelectrode surrounding'said grid electrode, a ring-like member,concentrically disposed with respect to said anode electrode anddisposed in spaced relation with respect to one end of said anodeelectrode, resilient supports extending radially inward from saidring-like member to equidistant positions intermediate said grid andanode electrodes, filament electrodes carried by said resilientsupports, means supporting said ring-like member and said anodeelectrode through the walls of said enclosing vessel for minimizingrelative displacement of said filament and anode electrodes underconditions of vibration, and a tubular member of dielectric materialsurrounding said grid electrode and disposed in spacial relation withrespect to said grid electrode and said filament electrodes andsupported at one end thereof from said ringlike member whereby saidtubular member of dielectric material is displaceable longitudinally andtransversely under condition of vibration without abutting with eithersaid grid or filament electrodes.

AUGUSTE LOUIS MARIE ANTOINE ROUY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,291,441 Donle Jan. 14, 19191,464,104 Nicolson Aug. '7, 1923 1,619,318 Summers Mar. 1, 19271,803,850 Hochstetter May 5, 1931 1,991,632 Scofield Feb. 19, 1935FOREIGN PATENTS 15 Number Country Date 725,362 France Feb. 12, 1932

